CATV networks refer to communications networks that are used to transmit cable television, telephone, broadband Internet signals and/or other information signals between one or more service providers and a plurality of subscribers, typically over coaxial and/or fiber optic cables. Most conventional CATV networks comprise hybrid fiber-coaxial networks in which fiber optic cables are primarily used to carry signals from the headend facilities of the service provider to various distribution points, while coaxial cable may be used, for example, to carry the signals into neighborhoods and to individual homes, apartment complexes, hotels, businesses, schools, government facilities and other subscriber premises (i.e., the physical locations of the subscribers).
Typically, the service provider is a CATV service provider that may have exclusive rights to offer cable television services in a particular geographic area. The service provider may broadcast a broad variety of CATV channels to the various subscriber premises over the CATV network. Most CATV service providers also offer other services such as, for example, broadband Internet service and digital telephone service. Thus, in many cases, a subscriber may receive CATV service, a broadband Internet connection, and Voice-over-Internet Protocol (“VoIP”) telephone service all through a single connection over the CATV network between the service provider and the subscriber premise.
To provide these services to individual subscriber premises, radio frequency (“RF”) tap units are typically connected in series along communications lines (e.g., a coaxial cable) of the CATV network. These tap units typically have an input port that connects to a first segment of the communications line, an output port that connects to a second segment of the communications line, and one or more RF tap ports. Each tap unit splits the signal that is received at its input port, allowing some of the received signal energy to pass through the tap unit to the output port (and thus the tap unit provides a communications path between the first and second segments of the communications line), while the remainder of the received signal energy is split further and provided to the RF tap ports of the tap unit. Cables, such as, for example, coaxial drop cables, may run between each RF tap port of a tap unit and a respective subscriber premise. In this manner, each RF tap port acts as a branch off of the communications line that is used to provide a communications path between the service provider and an individual subscriber premise over the CATV network. RF signals are transmitted through each RF tap port between the CATV network and an individual subscriber premise. Typically, a tap unit will include multiple tap ports (e.g., four or eight RF tap ports). Thus, each tap unit may be used to provide a communications path between a plurality of subscriber premises and the CATV network. Within the subscriber premise the received signal may be split further and fed to multiple devices, and may be amplified if required.
Two-way communications are typically supported between the CATV network and individual subscriber premises. The information that is transmitted from the CATV network headend facilities to the individual subscriber premises is typically referred to as the “downstream” and/or as the “forward path” communications, while communications from each subscriber premise to the CATV network headend facilities are typically referred to as “upstream” or “reverse path” communications. In a typical CATV network in the United States today, the downstream communications are transmitted over the 54-1002 MHz frequency band, while the upstream communications are transmitted over the 5-42 MHz frequency band. Other frequency bands are used in other countries, and modification of the above-referenced frequency bands in the United States is also under consideration. A signal amplifier is typically provided at each subscriber premise that may used to, among other things, amplify one or both of the downstream and/or upstream signals to compensate for signal loss that occurs on the coaxial cables that are connected between each tap unit and the individual subscriber premises or to compensate for the signal lost in splitting services between multiple devices in the subscriber premises.
Unwanted noise signals are often generated in individual subscriber premises, particularly at the lower end of the upstream frequency band. This noise may be generated, for example, by poor grounding, faulty equipment and/or improper installation of equipment and/or premise cabling. This noise funnels back into the CATV network. The proliferation of electronic devices that emit microwave signals (e.g., cellphones, cordless telephones, tablet computers, wireless routers, gaming devices, Bluetooth enabled equipment, etc.) has acted to increase the amount of noise that may funnel back into the network through faulty connections. This upstream noise can render portions of the upstream bandwidth essentially unusable (e.g., the 5-12 MHz frequency range), thereby limiting the bandwidth available for upstream communications. As CATV networks migrate to higher levels of data compression such as 64 or 128 QAM and/or implement DOCSIS 3.0 channel bonding signaling technologies in order to increase throughput, the upstream communications may become more sensitive to unwanted noise signals that are generated in individual subscriber premises.